DESCRIPTION: (provided by the applicant) Caveolae are a plasma membrane specialization that has been studied for over forty years. This work suggests that caveolae are involved in a special endocytic pathway that carries molecules to the cytoplasm, the ER and across the cell. Caveolae are also appears to be sites where signal transduction is organized. Compartmentalization of signal transduction at these sites is important for the spatial and temporal control of signal transduction. Virtually, all we know about this membrane domain is based on studies of epithelial and fibroblast cells in culture. Importantly, very little is known about the function of caveolae in neuronal cells. The principal reason for this deficiency is the lack of acceptable markers for neuronal caveolae. The aim of the research proposal is to identify proteins that will serve as markers for caveolae in neuronal cells. The availability of the markers will make it possible to purify this domain and study its molecular biochemistry. Given the importance that caveolae play in endocytosis and signal transduction in non-neuronal cells, we anticipate a better understanding of neuronal caveolae will open up a new area of neuroscience research into the role of signal compartmentalization in these cells. We will achieve this goal in three steps. First, we will purify candidate caveolae membranes from synaptic plasma membrane using a procedure that we have previously published. Proteins specifically in this preparation will be sequenced and candidate marker proteins identified. Second, we will clone the marker proteins, make antibodies and use these probes to determine the locations of the protein in neuronal cells. We will look specifically for proteins that localize to invaginated membrane domains in nerve terminals that have the morphology of caveolae. Finally, we will use these probes to develop a structural and functional link between neuronal and non-neuronal caveolae. If successful, the identification of caveolae markers could lead to the development of new strategies for treating drug abuse. Whereas, many different signal transducing molecules have been identified and studied in various in vitro and in vivo context, little is known about the role that compartmentalization plays in the activity of these molecules. We believe that a clearer study of caveolae in the brain will lead to new therapeutic strategies for treating diseases that rely on signaling cascades that originate from caveolae.